1. Field of the Invention
The present invention relates to an apparatus for generating compression waves in a conductive liquid, such as a molten metal.
2. Description of the Related Art
There have been poured intensive efforts in developing a technique that generates compression waves in a molten metal contained in a container and aims at an improvement of the tissues after the solidification of the molten metal and an enhancement of refining capabilities. However, it is considered difficult, at the present stage, to efficiently achieve a higher strength of the compression waves, and satisfactory results have not yet been accomplished.
Accordingly, it is an object of the invention to provide an apparatus for generating compression waves in a conductive liquid contained in a vessel, which improves an ac electromagnetic force applying means that generates the compression waves directly in the conductive liquid contained in the vessel, and thereby enhances the strength of the compression waves sufficiently.
In order to accomplish the foregoing object, the invention discloses an apparatus for generating compression waves in a conductive liquid, which comprises a vessel containing a conductive liquid and an ac electromagnetic force applying means that generates the compression waves in the conductive liquid contained in the vessel, in which an ac frequency f of the ac electromagnetic force applying means is set within a range given by the following [expression 1]:       2                  L        2            ⁢      π      ⁢              xe2x80x83            ⁢      μ      ⁢              xe2x80x83            ⁢      σ        ≦  f  ≦                    c        2            ⁢      μ      ⁢              xe2x80x83            ⁢      σ              2      ⁢              xe2x80x83            ⁢      π      
Here,
f: frequency (a major frequency when a wave-form of an electromagnetic force is developed by the Fourier transform, in case of the wave-form being a non-sine wave)
L: characteristic length of the system (for example, a depth, a radius of the vessel containing the conductive liquid)
xcexc: permeability of the conductive liquid
"sgr": electric conductivity of the conductive liquid
c: propagation velocity of the compression waves in the conductive liquid
Further, the invention discloses an apparatus for generating compression waves in a conductive liquid, in which the ac electromagnetic force applying means is an ac magnetic field generating electromagnetic coil, which is provided around the circumference of the vessel.
Further, the invention discloses an apparatus for generating compression waves in a conductive liquid, in which a dc magnetic field generating electromagnetic coil is provided around the circumference of the vessel.
Further, the invention discloses an apparatus for generating compression waves in a conductive liquid, in which the dc magnetic field generating electromagnetic coil is a superconducting magnet, and the vessel and the ac magnetic field generating electromagnetic coil are inserted in the bore of the superconducting magnet.
Further, the invention discloses an apparatus for generating compression waves in a conductive liquid, in which the ac electromagnetic force applying means comprises a pair of electrodes that are installed at positions on the circumferential wall of the vessel facing to each other so as to energize the conductive liquid, and an ac power supply connected to the electrodes.
Further, the invention discloses an apparatus for generating compression waves in a conductive liquid, in which the dc magnetic field generating electromagnetic coil is provided around the circumference of the vessel provided with the electrodes.
Further, the invention discloses an apparatus for generating compression waves in a conductive liquid, in which the dc magnetic field generating electromagnetic coil is a superconducting magnet, and the vessel with a pair of the electrodes is inserted in the bore of the superconducting magnet.
Further, the invention discloses an apparatus for generating compression waves in a conductive liquid, in which the vessel is formed of ceramics and provided with a metal reinforcing material on the circumference thereof, and an ac magnetic field generating electromagnetic coil as the ac electromagnetic force applying means is provided overlying the vessel.
Further, the invention discloses an apparatus for generating compression waves in a conductive liquid, in which the dc magnetic field generating electromagnetic coil is provided around the circumference of the vessel.
Further, the invention discloses an apparatus for generating compression waves in a conductive liquid, in which the dc magnetic field generating electromagnetic coil is a superconducting magnet, and the vessel is inserted in the bore of the superconducting magnet.
According to the present invention relating to the aforementioned apparatus for generating compression waves in a conductive liquid, since the ac frequency of the ac electromagnetic force applying means that generates the compression waves in a conductive liquid contained in a vessel is set within an appropriate range by the reason described later, the compression waves can be generated with a sufficient strength. Thereby, degassing of the conductive liquid and micro structuring of the tissues are effectively processed, and material improvement after the solidification of the conductive liquid will be brought about efficiently.
And, when the ac magnetic field generating electromagnetic coil as the ac electromagnetic force applying means is installed around the circumference of the vessel, the compression waves will be generated in the conductive liquid with a simplified construction and a low cost.
And, when, in addition to the ac magnetic field generating electromagnetic coil, a dc magnetic field generating electromagnetic coil is further installed around the circumference of the vessel, the superimposition of both the electromagnetic coils effects a stronger generation of the compression waves in the conductive liquid contained in the vessel. Thereby, enhancement of the refining capabilities after the solidification of the conductive liquid and improvement of the tissues will sufficiently be accomplished.
Further, when, while the dc magnetic field generating electromagnetic coil is made up with a superconducting magnet, the foregoing vessel and the ac magnetic field generating electromagnetic coil are inserted in the bore of the superconducting magnet, the superimposition of both the dc magnetic field generating electromagnetic coil as the superconducting magnet and the ac magnetic field generating electromagnetic coil effects a still stronger generation of the compression waves in the conductive liquid contained in the vessel, and material improvement after the solidification of the conductive liquid is achieved still more efficiently.
Further, when the ac electromagnetic force applying means is made up with a pair of electrodes that are installed at positions on a circumferential wall of the vessel facing to each other so as to energize the conductive liquid in the vessel, and the ac power supply connected to the electrodes, and furthermore the dc magnetic field generating electromagnetic coil is installed around the circumference of the vessel, the ac magnetic field generating electromagnetic coil is not required. Accordingly, the total construction of the apparatus is simplified remarkably, and in addition, the compression waves are generated efficiently in the conductive liquid contained in the vessel so as to contribute to material improvement after the solidification of the liquid.
And, also in this case, when the dc magnetic field generating electromagnetic coil is made up with a superconducting magnet, in the bore of which is inserted the vessel with the electrodes, the effect of a strong electromagnetic force by the dc magnetic field generating electromagnetic coil as the superconducting magnet is superimposed on the effect by the ac electromagnetic force applying means by a pair of the electrodes, which generates the compression waves still more effectively in the conductive liquid contained in the vessel, thereby achieving material improvement after the solidification of the liquid.
Further, while the vessel maintains a sufficient strength reinforced by the metal reinforcing material, when it is provided with the ac magnetic field generating electromagnetic coil to overlie the vessel, the apparatus is able to generate intensified compression waves in the conductive liquid contained in the vessel without being influenced by the metal reinforcing material. Thus, degassing of the conductive liquid and micro structuring of the tissues are effectively processed, whereby material improvement after the solidification of the conductive liquid will be accomplished.
Further, when the superimposition effect by the ac magnetic field generating electromagnetic coil provided overlying the vessel and the dc magnetic field generating electromagnetic coil provided around the circumference of the vessel is configured to generate intensified compression waves in the conductive liquid contained in the vessel, the material improvement after the solidification of the conductive liquid will be achieved more appropriately.
And, when the dc magnetic field generating electromagnetic coil provided around the circumference of the vessel is made up with a superconducting coil in pursuit for the superimposition effect by association with the ac magnetic field generating electromagnetic coil provided overlying the vessel, a still stronger generation of the compression waves in the conductive liquid contained in the vessel will be brought about, and a sufficient material improvement after the solidification of the liquid will be accomplished.